Question

20£®ÄÜÓüò±ã·½·¨µÄÒªÓüò±ã·½·¨Ë㣮
$\frac{7}{9}$¡Á£¨$\frac{2}{3}$-$\frac{2}{7}$£©       $\frac{6}{11}$¡Á$\frac{7}{15}$¡Á10       $\frac{1}{3}$¡Á$\frac{3}{5}$+1
$\frac{1}{2}$+$\frac{5}{4}$¡Á$\frac{4}{5}$           $\frac{5}{7}$-$\frac{5}{9}$¡Á$\frac{5}{7}$          1-$\frac{21}{25}$¡Á$\frac{5}{7}$£®

Answer 1

·ÖÎö ¢Ù$\frac{7}{9}$¡Á£¨$\frac{2}{3}$-$\frac{2}{7}$£©£¬ÔËÓó˷¨·ÖÅäÂɼòË㣻  
¢Ú$\frac{6}{11}$¡Á$\frac{7}{15}$¡Á10£¬ÏÈÔ¼·ÖÔÙ¼ÆË㣻    
¢Û$\frac{1}{3}¡Á\frac{3}{5}+1$£¬ÏÈËã³Ë·¨£¬ÔÙËã¼Ó·¨£»
¢Ü$\frac{1}{2}+\frac{5}{4}¡Á\frac{4}{5}$£¬ÏÈËã³Ë·¨£¬ÔÙËã¼Ó·¨£»
¢Ý$\frac{5}{7}$-$\frac{5}{9}$¡Á$\frac{5}{7}$£¬ÏÈËã³Ë·¨£¬ÔÙËã¼õ·¨£»
¢Þ1-$\frac{21}{25}$¡Á$\frac{5}{7}$£¬ÏÈËã³Ë·¨£¬ÔÙËã¼õ·¨£®

½â´ð ½â£º¢Ù$\frac{7}{9}$¡Á£¨$\frac{2}{3}$-$\frac{2}{7}$£©  
=$\frac{7}{9}¡Á\frac{2}{3}-\frac{7}{9}¡Á\frac{2}{7}$
=$\frac{14}{27}-\frac{2}{9}$
=$\frac{8}{27}$£»

¢Ú$\frac{6}{11}$¡Á$\frac{7}{15}$¡Á10    
=$\frac{28}{11}$£»
  
¢Û$\frac{1}{3}¡Á\frac{3}{5}+1$
=$\frac{1}{5}+1$
=$1\frac{1}{5}$£»

¢Ü$\frac{1}{2}+\frac{5}{4}¡Á\frac{4}{5}$
=$\frac{1}{2}+1$
=$1\frac{1}{2}$£»

¢Ý$\frac{5}{7}$-$\frac{5}{9}$¡Á$\frac{5}{7}$ 
=$\frac{5}{7}-\frac{25}{63}$
=$\frac{20}{63}$£»

¢Þ1-$\frac{21}{25}$¡Á$\frac{5}{7}$
=$1-\frac{3}{5}$
=$\frac{2}{5}$£®

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